Salt & pepper the meat on both sides and let sit while the marinade is prepared. Combine the ingredients and mix until the onions are fully coated. Place meat in shallow pan and cover evenly with the marinade. Cover and let sit in the refrigerator for 2 to 6 hours.

If using a broiler, turn temperature all the way up. Flip meat over so marinade is under the meat. Put under broiler for 4-5 minutes, then pull out and flip again making sure at least half of the marinade is spread across the top. Put under the broiler for another 4-5 minutes.

On the grill, heat up grill on medium high heat. Scrape off half the marinade and reserve. Place on grill marinade side down. Spread remaining marinade on top of meat. Sear on grill 4-5 minutes and then flip over for another 4-5 minutes.

Let meat rest on cutting board for 5 minutes. Once rested slice at about ¼ inch across the grain and serve.